[SS/TWoN] Mind control

Yes, I agree with you that Enthrallment is rather high stakes, not unlike death caused by Destruction. The focus can be used for less severe stakes than total mind control, though. For example, "Convince him to speak to me." is perfectly valid, it doesn't have to be about total mind slavery every time.

Note that technically, the way I play, you can put death into stakes as a character's intent. It's just that the stakes get modified by propriety: "I want to kill him" becomes "We'll roll dice to see if he falls into the waterfall and out of this immediate story, reserving however the SG option to bring him back." Of course that latter is not said aloud in practice because we've already gone through the campaign propriety guidelines earlier - the players know that when we agree to "I kill him dead" stakes we really mean "Insofar as my character knows, he'll end up dead."

The above works for mental domination as well insofar as the group decides that this is a case of propriety - that is, they have to decide whether indefinite mind slavery fits into the stylings of TSoY. When I play a simple conflict stake of mind-slavery gets executed with the understanding that it's a temporary condition that might break whenever the victim gathers his resolve for a Resist check - usually at a dramatic moment. Accomplishing something like completely and irreversibly breaking another's mind is handled exactly like death - you might think that you succeeded, but they always have some inner reserves they might draw on when the moment is right to surprise us all with the tenaciousness of human nature. An extended conflict could be used to cause real, total mind-death, of course. And non-named NPCs, those often get handled with less jurisprudence, allowing the evil mind-fucker to break them with just as little compunction as that afforded to minor NPCs when a sword-wielding murderer comes calling.

Three-Corner magic is also temporary, so it's not very good for truly breaking a person. I'd probably use alchemy for ruining lives in this manner as a first pick.